Electroweak Measurements at the Z-pole and the Zbb Couplings

Between the LEP and SLD experiments there was always a discrepancy in their determination of the weak mixing angle. This is mainly driven by the LEP b-asymmetry (Abbf) measurements, the single most precise measurement of that quantity at LEP, and the SLD left right asymmetry, Alr. Now when the lepton coupling results from LEP and SLD are all in good agreement, LEP versus SLD discrepancy could be speculated as an Ab deviation (which is also slightly favored by the SLD direct Ab measurement). The asymmetry measurements Ab/c are sensitive to the right handed Z ff couplings complementary to the partial widths measurements Rb/c which are more sensitive to the left handed couplings. However only SLD, utilizing the initial electron beam polarization, was pursuing a direct Ab measurement, while with LEP Abbf measurements one had to assume either Standard Model (SM) leptonic couplings to deduce Ab or to assume SM value for Ab to derive the electroweak mixing angle. measurements in Heavy Flavor physics rely on the ability to detect the secondary vertices from the b or c mesons weak decays and resolving them from the primary interaction vertexes. This is essential for background rejection. The technology of silicon vertex detectors which provides an adequate spatial resolution plays a major role in the heavy flavor experimentation. This was demonstrated by all LEP experiments and the best performance in this respect was realized at the SLC/SLD where the small and stable beam spot + a superb 3-D CCD pixel vertex detector has provided an excellent primary and secondary vertex resolution. The last SLC run of 97-98 almost tripled the total SLD data sample and that with a much improved vertex detector. SLD is about to release new results which will significantly improve Rb/c and Ab/c precision based on improved detector resolution and the increased statistics. There is also an effort at the LEP experiments to improve their LEP1 analyses. The LEP2 increasing energies allow as well measurements of the asymmetries and their energy dependence at energies higher than the Z0 peak